Mixed Bed De-ionizer (water de-ionizer) is based on the deionization technology.
Principle of operation
Deionizers remove both cationic and anionic impurities releasing H+ ions and OH- ions in exchange of cationic and anionic impurities respectively, these ions (H+ and OH-) subsequently combine to form pure water.
Figure showing ion exchange (Na+ ions are replace by H+ ions and Cl- ions are replaced by OH- ions, these ions combine later to form water)
| Deionizer for replacing cationic impurities with H+ ions | Deionizer for replacing anionic impurities with OH- ions |
Mixed Bed De-ionizer contains both the cation and anion resins in a single vessel. This produces water which is required for high pressure boiler feed water application, semi conductor and microelectronic industry application. The purpose of mixing the resins is to achieve a very high quality deionized water. When the resins are mixed, as the water passes through the resin bed it encounters a cation resin bead, then an anion resin bead, then cation, anion, cation, anion and so forth. The water is deionized then re-deionized continually resulting in an ultra high purity product.
As Mixed Bed De-ionizers produce water of high ionic quality but one major disadvantage of the Mixed Bed De-ionizers is that they do not remove bacteria/ endotoxin. Therefore it is recommended to follow the De-ionization purification with equipment that removes bacteria/endotoxin such as ultra purification, steam distillation and ultraviolet radiation. Other disadvantage of Mixed Bed De-ionizer is that as it utilizes both cationic and anionic resins and these typically will not reach exhaustion simultaneously. Consequently effluent water may become either extremely acidic or extremely alkaline, depending on which resins reach in exhaustion first.
Mixed Bed De-ionizer is useful in many following applications
• High pressure boiler feed water application,
• Semi conductor
• Microelectronic industry application
• Pharmaceutical plants
• Food and dairy processing plants
• Humidification system
• Steam generators